DESCRIPTION: This twice revised continuation application presents plans to analyze the relation between trigeminal motor function and the pattern of craniofacial growth. Plans are proposed to implant microspheres containing the excitatory neurotransmitter glutamate in proximity to the trigeminal motor nucleus of the rat. There are three Aims: 1) to investigate the morphological sequelae in the craniofacial system due to altered trigeminal motor activity, 2) to assess alterations in mandibular movement and EMG activity in the masticatory muscles in animals with implanted glutamate microspheres and 3) to ultimately define the potential of using impregnated microspheres as a system to treat craniofacial growth disorders.The current proposal is attempting to determine the dose-response levels of glutamate that can most efficaciously alter neuromuscular activity with its attendant change in craniofacial structure. In addition, HPLC and immunocytochemistry techniques will attempt to determine the site of glutamate binding at the level of the trigeminal motoneurons or premotor neurons that project to them.